The metabolic effects of oat and barley beta-glucans are largely due to their physical properties as soluble, viscous dietary fibers. These beta-glucans can hold onto water, creating a gel-like consistency in the gastrointestinal tract. This can have many effects, including slower gastric emptying, reduced digestion and absorption of glucose, and enhanced elimination of bile acids (which can have the downstream effect of lowering cholesterol).[1]
Fungal beta-glucans from yeast or mushrooms may produce immune-modulating effects by binding to pattern recognition receptors on immune cells in the gastrointestinal tract. This can lead to the initiation of an immune response by the innate immune system, which might include the activation of macrophages, neutrophils, and natural killer cells. Still, changes in the levels of immune cells or the compounds they produce (e.g., cytokines) are not consistently found.[2][3]
Lastly, interactions between beta-glucans and the gut microbiome may contribute to the effects of beta-glucans, in terms of both their metabolic effects and their immune-modulating effects. Preclinical research suggests that beta-glucans may have prebiotic properties, meaning they could promote the growth of beneficial microorganisms in the gut which may provide health benefits to the body. However, there’s currently no clinical research connecting the benefits of beta-glucans to microbiome modulation.[4]